In automotive applications, there is a push for energy efficiency. As some auxiliary components for internal combustion engines in motor vehicles are not required to run at all times, there has been an increase in efforts to isolate these auxiliary components when not in use. In the past, these components were connected to the engine drive via belts or chain drives, and engaged irrespective of need during running of the internal combustion engine. This negatively affects the motor vehicle efficiency, particularly with respect to fuel consumption.
Additional efficiencies can be gained for example, by having a water pump which is inactive upon cold starting of an engine so that the engine can come up to the running temperature more quickly, which also increases efficiency. Systems for deactivating a water pump include a moveable cover which covers the vanes of the pump impeller when the water pump is not required. However, in such systems, the water pump is driven constantly by the chain or belt drive, but the coolant is not pumped through the cooling jackets of the engine due to the cover over the vanes of the impeller. Another known solution provides an electro-magnetic clutch between the bearing and the drive pulley for the water pump. However, this solution requires additional space and has a weight penalty. Further, many additional parts are required to achieve functionality. Additionally, the energy required for operation is comparatively high due to the method of operation adopted from conventional electro-magnetic/mechanical clutch systems.
It would be desirable to provide a clutching function for disconnecting auxiliary drive components when not needed, particularly in connection with internal combustion engines for motor vehicles, which has a small space requirement, low weight, and low cost.